Tube



H. H. WRIGHT Dec. 5, 1933.

TUBE

Filed Oct. 31, 1931 ATTORNEY and demands replacement.

Patented Dec. 5, 1933 Henry H. Wright,

Snyden N. Y., assignor to Du Pont Cellophane Company, Inc., New York,

N. a corporation of Delaware ApplicationfOctoberBl, 1931. Serial N o. 5'7f?,,266

lClaim. (c1. 250-275).

turer used or burned out tubes as defective ones. Again, many unscrupulous dealers sell used tubes as new ones with the result that .the purchaser receives a tube which burns out considerably before its guaranteed life. As a consequence, the user complains to the manufacturer It is apparent that these practices not only are vexpensive to the. manufacturer butalso tend to destroy the good will built up by it. i l

I have found that the above-mentioned prac-' tices may be overcome by applying on the base of the tube a temporary protective covering consisting of a cap of regeneratedlcellulose which intimately and snugly grips the base and covers,

the contact elements.

It is therefore an object of this invention to provide tubes, such as incandescent lamps, radio tubes and the like, with protective coverings disposed onthe base thereof and completely covering the contact elements.

Other objects of the invention will become apparent from the following description, appended claim and accompanying drawing forming a part of this specification and in which Figure 1 illustrates a vertical section of a regenerated cellulose cap prior to its disposition on the tube;

Figure 2 is a side elevation, partly in section, showing the cap in position on a radio tube;

and

Figure 3 illustrates the side elevation of an electric light lamp, partly in section, illustrating the protective cap applied thereto.

Referring to the drawing wherein like referencenumerals designate like parts, and particularly to Figure 2, the reference numeral 1 designates a bulb of an ordinary radio tube mounted on a base 2 on which the usual filament 3 with its appurtenant cooperative parts, such as grids and the like, are secured. Disposed on the exterior end of the base 2 are a plurality of electric contact elements, such as prongs 4, by means of which the tube is inserted in the electrical circuit of the apparatus in whichit is to -be us'ed.lf As previously statedfone-of the essential features'of this invention is to provide the tube with a protective covering which will insure the pur- I chaser .of receivinga new tubefland also topre vent the dealers fromreturningi-used. tubes as defective, ones tothe manufacturer for replacement. With this inviewthere is disposed on the base 2 a cap dwhich intimately and tenaciously adheres to those portions .of thertub'e which it engages. f

The cap 5 may be formed of any material which, for reasons which will become apparent; shrinks upon conversion from the wet to the dry state:

As several examples of materials which possess this property may be mentioned regenerated cel 7 procedure ,may comprise coating a mandrel; as

by immersing it in a viscose solution. .Thecoated mandrel is-then subjected to a coagulating and regeneratinggbath, whereby the cellulose: is re sot generated from the viscose solution.- .The regen erated cellulose capmayy-if desired, then be sub jected to the desulphurin'g, bleaching and washing steps, afterwhich'they are disposed in waterfanda kept there until used. 1

It is apparent that the cap may be transparent or opaque as well as colored." ,When an opaque cap is desired, the finished-cap may be appropriately treated or the result may be achieved by,"

introducing in the molding solution an opacity inducing agent. It is of course understood that by opaquing the cap with colored pigments or other coloring'agents the cap will also be colored. When the cap is to be transparent and colored,

the cap may be dyed or a dyestuff of the desired color incorporated in the solution'to bemolded.

The cap in thewet condition is usually oversize, with the result that it can' very easily and expeditiously be applied in position. After the proper disposition of the cap, it is permitted to v dry or is subjected to a drying treatment, during whichthe cap, by virtue of its properties above mentioned, shrinksto a considerable ex tent with the consequence that it intimately and snugly grips the base 2 and completely ,covers the prongs 4. The length of the skirt 6 of the'cap 5 may vary within wide limits. It may be or such. length that it completely covers the base 2 and/or also extendson tothe bulb 1. on the other hand, the skirt 6 of the cap 5 may be of such a length that it merely extends over a portion of the base 2. 1

The cap may also be provided with any identifying or advertising indicia, such as the name of the manufacturer, patent numbers, tradenames, or. the like. In the event that a transparent cap is used, any indicia on the base will be visible.

A radio tube provided with the protective cap as above described is packed in the usual cartons and so distributed to the various dealers. "When a prospective customer desires to buy the tube,

the retailer removes it from the box and in View of the customer punctures the cap so that the prongs extend thereover, in which condition the tube is tested. This procedure assures the purchaser receiving a factory-newtube. It also prevents unscrupulous dealers from returning to the manufacturer used tubes as defective ones.

Theuser or service man, prior'to inserting the tube in the circuit, removes the cap from the tube .by. the simpleoperatio n of manually stripping it therefrom withj or without the aid of any-suitableimplement, such as a pocket knife. To facilitate the manual stripping operation and eliminatethe use of-auxiliary devices, the cap maybe providedwith-a tab 7 which maybe gripped and pulled-upwardly,with the result that the. cap is easily removed. Likewise, the removal operation may be more conveniently performed by utilizing a'rip string 8 in combination with the cap.

' Figure 3 discloses the application of the principles of this invention-employed in connection with incandescent lamp bulbs. Referring to Figure 3, the reference numeral 9 designates the ordinary incandescent lamp bulb mounted on a baselO which carries the filament l-lon one end thereof. ,On theopposite end, thefbase 10 isiprovided with the usual contact member 12. As in the'case of theradio tube, the cap 5, while in the wet condition, is disposed on the base, so that it completelycovers the exposed end (of the base 10 andhence alsothe contact element 12. In this modification, the skirt 6 of the cap 5 is preferably made of such a length that'it merelye'xtends over a portion of the base 10. As explained above,

- upon drying, the cap shrinks and intimately contacts and ten'ac'iously adheres to'th'e portions of the base with which it contacts. It [also conforms to the outline of the threads'l3 of the base and'does not interfere with its being-screwed into the testing socket. As in'the previous specific .permitthe usual handling of the tube.

exemplification of the inventiomthe cap may be transparent, opaque, colored, or decorated in any appropriate manner.

- The skirt 6 of the cap 5 is made to extend over 7 a portion of the base, 10 so that some of the threads 13 will be exposed and may be capable of being used as one of the contacts of the circuit. 1 In use asin the case of the'radio tube, the cap may be punctured so that the' contact element 12 is exposed. When this procedure .is employed, the

:usual testing socket may be used. If desired,

however, an improvised testing socket may be utilized. Such a socket could, forexample, comprise a contact element adapted to cooperate V with-the-element 1 2 and which, when the bulb 'is beingpositioned' inplace, would rupture the cap and therefore permit its contact with the ele--. ment 12. Such a testing socket could have its other-contact disposed so that it would engage the uncovered threads 13. 1

The cap is sufficiently rugged and tough to N0 addi i io prongs 'on the base thereof -whereby "the tube Y may be disposed-in an electrical circuit andthe filament and appurtenant elements within the tube energized, a temporary proteetivecap formed of aj materialof the class which comprisesgelatine, cellulose acetate and regenerated cellulose, said cap be'ing sMun-kin position-on said base, the skirt of said cap intimately gripping andconformingto the'shape of at'least-a portion of the peripheral surface of said base to securely-position said cap/and the top of said cap "extending over and'fcoverin'g the'freeextremities of all the contact prongs and engaging the ends of said'pron'gs to prevent-normal actual use of said tube.

HENRY H. WRIGHT. 

